What is reason for raise in fuel consumption of a ship?

Followings could be some reasons for raise in fuel consumption of a ship:

1- Bad quality fuel

2- faulty fuel pump/ fuel valves (main engine)

3- ship's bottom being dirty

4- faulty turbo charger (main engine)

5- blow by of the piston rings (main engine)

5- leaky inlet/exh. valves (main engine)

6- leakage in fuel system (pipping)

7- faulty fuel oil separator

8- Unprefect bunckering

9-.....etc.